JPH0618986B2 - Curable epoxy resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable epoxy resin composition, and more particularly to a curable epoxy resin composition modified with a moisture curable silicone rubber.

<< Prior Art >> Epoxy resin compositions have not only electrical properties such as dielectric properties, volume resistivity, and dielectric breakdown strength, but also bending strength, compressive strength,
Because of its excellent mechanical properties such as impact strength, heat resistance, and adhesiveness, it is widely used as an insulating material for various electrical and electronic parts as well as adhesives and various composite materials.

However, recently, with the progress of thinning and miniaturization of electronic parts and the increase in size of semiconductor chips due to the increase in the degree of semiconductor integration, package material cracks, silicon chip cracks, passivation cracks, wiring movements, epoxy resin itself Problems such as cracks and a gap between the electric / electronic component and the epoxy resin, and a failure caused by the intrusion of water through the gap are increasing.

As a method for improving such a defect, conventionally, (1) a method of adding a resin that imparts flexibility to an epoxy resin (for example, JP-A-54-81360 and JP-A-57).
-56954) (2) A method of blending a large amount of an inorganic filler such as silica or alumina having a small coefficient of thermal expansion, (3)
To the curable epoxy resin, add curable silicone rubber and carbon functional silane and mix,
A method such as improving the crack resistance of the cured epoxy resin by curing at the same time (JP-A-55-3412) has been adopted.

However, although the first method is effective as a method for preventing crack generation in the epoxy resin itself, it brings about a decrease in hardness at the time of heating and glass transition temperature, which are excellent properties inherent to the epoxy resin, and the high temperature of the epoxy resin. There was a drawback that the characteristics were impaired. On the other hand, in the second method, a cured product having a desired thermal expansion coefficient can be obtained, but the fluidity of the epoxy resin composition is remarkably reduced, so that casting, transfer molding, potting, powder coating, dropping, etc. However, there is a drawback in that the Young's modulus of the epoxy resin increases and the reduction of the internal stress due to the reduction of the thermal expansion coefficient cannot be expected so much.

In the third method, the curable silicone rubber is cured in a curable epoxy resin in a dispersed state, so that the curing reaction does not proceed completely and unreacted substances remain. At times, there are drawbacks such as stains on the mold, deterioration of printability on the cured product, and overcoating. Such a drawback is that the thermosetting silicone resin composition is gelled as dispersed particles under stirring in a state in which gelation of the thermosetting resin composition is suppressed,
Then, the thermosetting resin composition can be cured to significantly improve the composition (Japanese Patent Laid-Open No. 56-14556).
issue). Although this method is excellent in that the silicone resin can be finely dispersed in the thermosetting resin, after all,
Since the compatibility between the thermosetting resin and the silicone resin is poor, the latter gradually floats, and there is a drawback that the uniformity of the entire cured product is naturally limited. Such a drawback is that the epoxy resin and the curing material as well as the pre-cured linear organopolysiloxane block
The thermosetting epoxy resin composition (Japanese Patent Laid-Open No. 58-219218) consisting of a polymer cured product containing 0% by weight or more similarly exists. Furthermore, in this case, the particulate dispersion to be dispersed must be obtained by pulverizing the cured product into particles, which is not only complicated but also difficult to narrow the particle size distribution. In that sense as well, the homogeneity of the cured product of the thermosetting epoxy resin composed of the above composition is not always sufficient, and in order to improve the compatibility with the epoxy resin, the linear organopolysiloxane block There is a drawback in that the modification of the epoxy resin composition naturally has a limit in that the degree of polymerization and the content must be limited.

<< Problems to be Solved by the Invention >> Therefore, as a result of intensive investigations by the present inventors in order to solve such conventional drawbacks, the polyether-modified organopolysiloxane is extremely effective as a compatibilizer for silicone rubber and epoxy resin. In addition to the fact that the silicone rubber can be easily finely dispersed in the epoxy resin by using this, it is possible to realize a homogeneous and dense sea-island structure without the silicone rubber floating. The inventors have found out what can be done and have reached the present invention.

Therefore, an object of the present invention is to provide a uniform curable epoxy resin composition having improved impact resistance and moisture resistance.

<< Means for Solving the Problems >> The above object of the present invention has been achieved by a curable epoxy resin, a moisture curable silicone rubber composition and a curable epoxy resin composition containing a polyether-modified organopolysiloxane as a main component. .

The curable epoxy resin as the first component used in the present invention is a curable epoxy resin composed of an epoxy resin having two or more epoxy groups in one molecule and various curing agents. There are no particular restrictions on the molecular structure, molecular weight, etc., as long as it can be cured by various curing agents as described below, and it can be used by appropriately selecting from various conventionally known epoxy resins. . Examples of such substances include diglycidyl ether of bisphenol A, epibis type epoxy resin which is a multimer thereof, bisphenol F type epoxy resin, resorcin type epoxy resin, etrahydroxyphenylethane type epoxy resin, cresol novolac. Type epoxy resin, polyolefin type epoxy resin, alicyclic epoxy resin and their halides.

In using the above-mentioned first component, a monoepoxy compound may be appropriately used in combination, and examples of the monoepoxy compound include styrene oxide, cyclohexene oxide, propylene oxide, methyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, Examples include allyl glycidyl ether, octylene oxide, dodecene oxide and the like. The first component is not necessarily limited to only one kind in use, and two or more kinds may be mixed and used.

As the curing agent for the epoxy resin, diaminodiphenylmethane, diaminodiphenyl sulfone, amine-based curing agents represented by metaphenylenediamine, phthalic anhydride,
Examples thereof include acid anhydride-based curing agents such as pyromellitic dianhydride and benzophenonetetracarboxylic acid anhydride, and phenol novolac curing agents having two or more hydroxyl groups in one molecule such as phenol novolac and cresol novolac. Even if these curing agents are used alone, 2
One or more species may be used simultaneously, but in any case, an amount sufficient to cure the epoxy resin is used.

Further, in the present invention, various curing accelerators for the purpose of accelerating the reaction between the above curing agent and the epoxy resin, for example, imidazole or a derivative thereof, a tertiary amine derivative,
A phosphine derivative, a cycloamidine derivative, etc. can be used together.

In the present invention, a moisture-curable silicone rubber composition is used as the second component to modify the curable epoxy resin composition. By using the moisture-curable silicone rubber composition in this way, it is possible to avoid the adverse effects of the curing accelerator of the epoxy resin, and to independently control the curing of the silicone rubber and the curing of the epoxy resin. You can When an addition-curable silicone rubber composition is used, the curing accelerator of the epoxy resin acts as a catalyst poison for the catalyst used for curing it, so curing of the silicone rubber and curing of the epoxy resin are prevented. It is difficult to control each independently.

A) General formula (Wherein R ¹ and R ² are the same or different, unsubstituted or substituted monovalent hydrocarbon groups, m is an integer of 5 or more) 100 parts by weight of diorganopolysiloxane having both ends of the molecular chain blocked with hydroxyl groups , B) General formula R ³ _4-a SiX _a (wherein R ³ is an unsubstituted or substituted 1 hydrocarbon group, X is a hydrolyzable group, and a is 2 <a
<A positive number of 4) 0.5 to 30 parts by weight of organosilane or a partial hydrolyzate thereof, C) 0 to 100 parts by weight of fumed silica, D) 0 to 10 parts by weight of a curing catalyst, Can be given.

The diorganopolysiloxane as the component A) may be a conventionally known raw material for a silicone rubber in which both ends of the molecular chain are blocked with hydroxyl groups. And R ¹ and R ² are alkyl groups such as methyl group, ethyl group, propyl group, butyl group, alkenyl groups such as vinyl group and allyl group, aryl groups such as phenyl group, cycloalkyl groups such as cyclohexyl group. The same or different unsubstituted or substituted monovalent hydrocarbon groups selected from groups or groups in which some or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc.,
m is an integer of 5 or more. The diorganopolysiloxane represented by the above general formula cannot obtain a cured elastic body having an excellent physical strength when the clay is 100 cs or less, and the composition of the present invention when the clay is 1,000,000 cs or more. Since the clay is too high and the workability at the time of use deteriorates, the clay is preferably in the range of 100 to 1,000,000 cs,
Particularly, those in the range of 3,000 to 50,000 cs are preferable. Further, this diorganopolysiloxane has a substantially linear structure, but it may be one having a three-dimensional structure of siloxane introduced therein as long as it is in a small amount.

Next, the component B) which constitutes the composition of the present invention is a known component which reacts with the above-mentioned diorganopolysiloxane as the component A) at room temperature to act as a curing agent for curing it. As described above, the general formula R ³ _4-a SiX _a
R ³ is an unsubstituted or substituted monovalent hydrocarbon group similar to R ¹ and R ² described above, X is an acyloxy group, an alkoxy group, a ketoxime group, an alkenyloxy group, an amino group, an aminooxy group, A hydrolyzable group selected from amide groups and the like, a is organosilane or a partial hydrolyzate thereof, which is a positive number of 2 <a <s. The organosilane should have at least two hydrolyzable groups in its molecule. Examples of such an organosilane include CH ₂ ═CHSi (OCOCH ₃ ) ₃ , CH ₃ Si (OCOCH ₃ ) ₃ , And partial hydrolysis products thereof. If the amount of component B) added is 0.5 parts by weight or less relative to 100 parts by weight of component A), the curing and crosslinking reaction of this composition in the presence of moisture will be insufficient.
If the amount is 0 parts by weight or more, the cured product becomes too hard.
It is necessary to set it in the range of 0.5 to 30 parts by weight,
A particularly preferred range is 2 to 15 parts by weight.

Further, the fumed silica as the component C) in the composition of the present invention is conventionally known as a raw material for silicone rubber. This is an optional component, but since it serves as a reinforcing material for imparting mechanical strength to the cured product obtained from the composition of the present invention, its specific surface area is at least 50 m ² / g. preferable. Further, this may be surface-treated with dimethylpolysiloxane, tetramethyldisilazane, dimethylchlorosilane, or the like. The amount of fumed silica added is 3 to 3 parts by weight with respect to 100 parts by weight of the component A), and the reinforcing strength is insufficient. If it is 100 parts by weight or more, the cured product becomes too hard. It is in the range of 100 parts by weight, particularly preferably in the range of 3 to 25 parts by weight.

The component D) is a catalyst that promotes the reaction between the components A) and B) described above, and is, for example, an organic carboxylic acid such as lead-2-ethyloctoate, dibutyltin diacetate or dibutyltin dilaurate. Metal salts; tetrabutyl titanate, tetra-2-ethylhexyl titanate,
Organic titanate ester such as; organotitanium compounds such as organosiloxy titanium and β-carbonyl titanium; N
Amine compounds such as aminoalkyl group-substituted alkoxysilanes such as-(trimethoxysilylpropyl) ethylenediamine, hexylamine, and salts thereof; dialkylhydroxylamine such as dimethylhydroxyamine, diethylhydroxylamine; tetramethylguanidylpropyltrimethoxysilane And other guanidine compounds.

In the present invention, the above component D) is not an essential component,
If necessary, it may be added in an amount of 10 parts by weight or less based on 100 parts by weight of the component A).

The composition of the present invention can be obtained by mixing predetermined amounts of the above-mentioned components A) to D) under anhydrous conditions. If necessary, various plasticizers, coloring agents such as pigments, Known additives such as heat or cold resistance improvers, flame retardants, antifungal agents, decolorizing agents, silane coupling agents, and adhesion improvers can be added.

The above-mentioned epoxy resin and silicone rubber composition have a so-called water-oil relationship, and it is extremely difficult to blend them. Particularly, this difficulty is remarkable as the hydrocarbon portion contained in the silicone rubber is small, and it is forced. Even if it is intentionally blown, it is unavoidable that the separation of the two gradually proceeds until the epoxy resin is cured.

Therefore, in the present invention, a special surfactant having a strong ability to reduce the interfacial tension is used as a compatibilizer so that the above-mentioned separation of the two does not occur. Such a special surfactant is a polydimethylsiloxane modified with a functional group having a strong affinity with an epoxy resin. In the present invention, a polyether-modified organopolysiloxane is particularly preferable among them. Is preferred. As such a modified organosiloxane, a general formula, [Wherein R ⁴ is And R ⁵ is a hydrogen atom, an atom or a group selected from a lower alkyl group and an acyl group, and k and l are 0 respectively.
Or a positive integer, a group represented by k + 1 ≠ 0, or (However, m is a group represented by 0 or 1), R ¹ is the same as R ¹ used in the section of component A, b and c are positive numbers (where 0 <b + c <4). . ] It is preferable to use the organopolysiloxane represented by

Of these, R ⁴ Are particularly preferable in that the impact resistance after curing can be improved.

<< Action >> These compatibilizers can be used alone or in combination of two or more, but in any case, by adding a certain amount or more of these compatibilizers, the compatibilizer and the epoxy resin The affinity of the silicone rubber component can be increased. It is considered that this is because the polyether portion has a strong affinity with the epoxy resin, while the polydimethylsiloxane portion is compatible with the silicone rubber composition. Such an idea itself is not different from the conventional one, but as will be clearly shown in Examples described later, the effect thereof is in the present invention in which the compatibilizing agent is used together with the moisture-curable silicone rubber composition. There is something amazing.

The amount of the compatibilizer used can be appropriately adjusted depending on the type of the compatibilizer, but with respect to the epoxy resin,
Add 0.1 wt% to 10 wt%. If the amount is less than 0.1% by weight, the curing as a compatibilizing agent is insufficient and 10
If it exceeds 5% by weight, the compatibilizing agent oozes out after curing and the physical properties of the cured product deteriorate, which is not preferable. A particularly preferable amount of addition is 0.5% by weight to 5% by weight.

The method of mixing the curable epoxy resin, the moisture-curable silicone rubber composition and the compatibilizer is not particularly limited, but the uncured moisture is mixed while vigorously stirring the curable epoxy resin in which the compatibilizer is uniformly dispersed. It is preferable to add a curable silicone rubber composition and a catalyst for curing. The epoxy resin curing agent is preferably added after the uniform dispersion of the curable silicone rubber is substantially completed.

As described above, since the moisture-curable silicone rubber is used in the present invention, it is possible to reduce the energy cost at the time of manufacturing and to control the curing of the silicone rubber and the curing of the epoxy resin completely independently. Also,
The curing accelerator for the epoxy resin does not prevent the curing of the silicone rubber. Further, in the present invention, the curing of the silicone rubber composition can be completed without proceeding the curing of the epoxy resin. Therefore, not only is the manufacturing process simple, but the particle size of the silicone rubber particles can be made uniform and small.

The silicone rubber-containing epoxy cured product of the present invention produced as described above is particularly useful as a semiconductor encapsulating material because it has improved impact resistance and moisture resistance as compared with conventional ones.

<< Effects of the Invention >> According to the present invention, the silicone rubber contained in the obtained cured product is such that sufficiently fine particles are uniformly distributed, and the affinity between the silicone rubber and the epoxy resin is also good. Therefore, impact resistance and moisture resistance can be remarkably improved.

<Example> The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1. Measurement of Interfacial Tension Reducing Ability Using Epicoat 828 as a curable epoxy resin and using silicone oil KF96 (manufactured by Shin-Etsu Chemical Co., Ltd.), the interfacial tension reducing ability of various modified polydimethylsiloxanes was examined.

FIG. 1 is a graph showing the relationship between the interfacial tension γ ₁₂ with respect to the silicone oil of the epoxy resin / modified organopolysiloxane mixture system and the modified organopolysiloxane concentration. In the figure, the symbols are epoxy-modified organopolysiloxane X-60-164 (EPMPS): is glycidoxypropyltrimethoxysilane (GPTMS), is polyether-modified organopolysiloxane KF615A (E
TMPS) (all modified organopolysiloxanes are manufactured by Shin-Etsu Chemical Co., Ltd.).

As is clear from the results in FIG. 1, γ ₁₂ decreases with the addition concentration of any modified organopolysiloxane, but there is a large difference in the amount of decrease, especially in the case of polyether modified organopolysiloxane. It is clear that the effect is remarkable.

The relationship between the interfacial tension γ ₁₂ and the concentration C is It is represented by.

Here, γ _12.0 is the lowest value of γ ₁₂ , γ _12.Lim = γ ₁₂ at C = 0, and K is the surface activity coefficient.

The value of K obtained by plotting the logarithm of the left side of the above formula against the concentration is as shown in Table 1.

From the results shown in Table 1, it was found that the ether-modified organopolysiloxane having the maximum K was the most effective as the compatibilizing agent.

Next, in order to see how the action of the compatibilizer changes depending on the type of the polyether-modified organopolysiloxane used as the compatibilizer, instead of the silicone oil, a moisture-curable silicone rubber composition (Shin-Etsu Using KE108 manufactured by Kagaku Co., Ltd., three kinds of polyether silicones (all manufactured by Shin-Etsu Chemical Co., Ltd.) were evaluated in the same manner as above. The results are shown in Fig. 2 and Table 2.

As is clear from FIGS. 1 and 2, the γ ₁₂ of the pure epoxy resin was 8.99 dy at the interface with the silicone oil.
The decrease from n / cm to 6.48 tyn / cm is considered to be because the crosslinking agent contained in the moisture-curable silicone as a vulcanization base increased the affinity with the epoxy resin. It was also found that KF351 and KF355 in which the polyether block was only polyethylene oxide showed a small decrease in γ ₁₂ , and KF615 containing polypropylene oxide in the polyether block exhibited strong surface activity.

Manufacture of Cured Product KF615A, which was found to have the largest compatibilization and curing by the above evaluation, was used as a compatibilizing agent, Epicoat 828 as a curable epoxy resin, and bis-p-aminocyclohexylmethane (PACM) as a curing agent thereof. , 4'-
A blend was prepared as follows using diaminodiphenylmethane (DDM) and KE108 as the silicone rubber.

KF615A 0.5 g (1% by weight) as a compatibilizing agent in 49.5 g of curable epoxy resin (Epicoat 828)
Was added, and after sufficiently stirring to defoam, the catalyst was added to the moisture-curable silicone rubber (KE108), which was heated to 50 ° C. and vigorously stirred with a stirrer.
The rubber particles were dispersed into a milky white viscous liquid. After defoaming the obtained liquid, an equivalent amount of a curing agent 4,4′-diaminodiphenylmethane (DDM) was added, and the mixture was further stirred, defoamed, poured into a mold, and heated at 165 ° C. for 2 hours to be cured.

From the obtained cured product, 1 according to JIS K7110
Cut out a 2.7 × 12.7 × 63.6 mm test piece,
A notch having a depth of 2.54 mm was formed in the center and an Izod impact test was conducted.

FIG. 3 shows the relationship between the impact fracture energy (E) and the addition amount of moisture-curable silicone rubber (phr). This result demonstrates that the present invention significantly improved the impact resistance of the epoxy cured product.

Also, add 5 phr of moisture curable silicone rubber,
When the fractured surface of the system cured with ACM (P-aminocyclohexylmethane) was observed by SEM, it was confirmed that rubber particles of 1 to 20 μm were dispersed over the entire surface. It was confirmed that thyroxine is sufficiently effective as a compatibilizer. Furthermore, since it was observed that a small piece of epoxy resin was attached to the surface of the rubber particles, it was possible to infer that there was a considerable binding force at the interface between the epoxy resin and the moisture-curable silicone rubber particles.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the interfacial tension of an epoxy resin / modified organopolysiloxane mixed system with silicone oil and the modified organopolysiloxane concentration. FIG. 2 is a graph showing the relationship between the interfacial tension of an epoxy resin / polyether-modified organopolysiloxane mixed system with respect to a moisture-curable silicone rubber and the polyether-modified organopolysiloxane concentration. FIG. 3 is a graph showing the relationship between impact fracture energy and the amount of moisture-curable silicone rubber added.

Claims (1)

[Claims] 1. A curable epoxy resin composition comprising a curable epoxy resin, a moisture curable silicone rubber and a polyether-modified organopolysiloxane as a main component.